91978390177 has 2 divisors, whose sum is σ = 91978390178. Its totient is φ = 91978390176.

The previous prime is 91978390171. The next prime is 91978390187. The reversal of 91978390177 is 77109387919.

It is a weak prime.

It can be written as a sum of positive squares in only one way, i.e., 90735898176 + 1242492001 = 301224^2 + 35249^2 .

It is a cyclic number.

It is not a de Polignac number, because 91978390177 - 2¹⁵ = 91978357409 is a prime.

It is not a weakly prime, because it can be changed into another prime (91978390171) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (19) of ones.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 45989195088 + 45989195089.

It is an arithmetic number, because the mean of its divisors is an integer number (45989195089).

Almost surely, 2^91978390177 is an apocalyptic number.

It is an amenable number.

91978390177 is a deficient number, since it is larger than the sum of its proper divisors (1).

91978390177 is an equidigital number, since it uses as much as digits as its factorization.

91978390177 is an odious number, because the sum of its binary digits is odd.

The product of its (nonzero) digits is 6001128, while the sum is 61.

The spelling of 91978390177 in words is "ninety-one billion, nine hundred seventy-eight million, three hundred ninety thousand, one hundred seventy-seven".